1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves an undersea hydraulic coupling having an improved radial seal with a dovetail interfit with the female coupling member for holding and positioning the seal in place.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with seals to seal the junction between the male and female members. The female member generally has a cylindrical body with a relatively large diameter bore at one end and a relatively small diameter bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains the seals and receives the male portion of the coupling. The male member includes a probe section insertable into the large bore of the female member. According to various embodiments of the device, the seals either abut the end, or face, of the male member or engage the male member about its outer circumference. Hydraulic fluid is then free to flow through the female and male portions of the coupling and seals prevent that flow from escaping about the joints of the coupling.
Optionally, a check valve may be installed in the female member and also in the male member. Each check valve is open when the coupling is made up; however, each check valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is part.
In U.S. Pat. Nos. 4,694,859 and 5,762,106 to Robert E. Smith III, an undersea hydraulic coupling and metal seal is disclosed. A reusable metal seal engages the circumference of the probe when it is positioned within the female member body. The seal is held in place by a cylindrical body or retainer. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member.
U.S. Pat. No. 4,900,071 to Robert E. Smith III discloses an undersea hydraulic coupling with an elastomeric seal that is restrained from radial movement into the central bore of the female member by a circumferential shoulder on one or both surfaces adjacent the seal. Preferably, the seal has a dovetail interfit with one or both surfaces. U.S. Pat. Nos. 5,052,439, 5,099,882, 5,203,374, 5,232,021 to Robert E. Smith III also show undersea hydraulic couplings with these seals. An inner cylindrical surface of the annular seal engages the circumference of the male member or probe as the probe is inserted into the female member. As the male member or probe is pulled out of the female member bore, the leading face of the male member reaches the soft annular seal intermediate that bore. When the face reaches the midpoint of the soft annular seal, the dovetail interfit prevents the seal being imploded into the bore, as the seawater and/or hydraulic fluid enter the bore at high pressure.
If the probe of the male coupling member is imperfectly aligned with the female coupling member, it can drag against the female coupling bore or receiving chamber, and drag against each seal retained in the bore. The drag can result in galling to the surfaces of the respective coupling members. The drag also can damage the seals retained in the female coupling member, especially pressure energized radial metal seals that seal around the circumference of the male coupling member.
To help align the male coupling member when it enters the female bore or receiving chamber, some undersea hydraulic couplings include two or more redundant radial seals. Two or more seals provide guide points to help the male member enter the bore or receiving chamber without galling and damage to the sealing surfaces. Additionally, two or more redundant seals reduce the risk that hydraulic fluid will leak from the coupling at higher pressures and greater subseas depths. However, couplings designed for use of two or more such seals require additional components for retaining the seals, increasing the complexity and cost of the coupling design.
Accordingly, an undersea hydraulic coupling is needed having a seal or seals that can reduce the drag or galling when the male coupling member enters the female coupling member, but without the additional seal retaining components.
The present invention overcomes the above mentioned problems and disadvantages by providing an undersea hydraulic coupling with a ring-shaped elastomeric seal having two or more radial sealing surfaces at the inner circumference thereof. Each of the sealing surfaces at the inner circumference engages the probe of the male coupling member, providing guide points to help ensure proper alignment between the coupling members, prevent or reduce the risk that the male coupling member will drag against the female coupling member during engagement or disengagement, and prevent or reduce the risk of galling of the surfaces and seals retained therein.
On each side of the elastomeric seal, opposing inclined circumferential shoulder surfaces have an interfit with the seal and prevent the seal from imploding and/or radially moving into the bore upon separation of the female member and male member. The seal has inclined surfaces that interfit with the opposing inclined shoulder surfaces.